Biological membranes - Temperature and Solvents

Question 1

what is the effect of an increase in temperature on membranes

Answer 1

increase in kinetic energy, increase in movement, more fluid, permeable membranes

Question 2

why do high temperatures cause the membrane to become more permeable

Answer 2

phospholipids vibrate, causing them to be further apart. the bigger gaps allow larger molecules to pass through, the phospholipid bilayer is therefore more permeable

Question 3

what is the impact of very high temperatures on membranes

Answer 3

cause the phospholipids to move completely apart, causing the membrane to break down

Question 4

what will happen to protein structure in the membrane as temperature is increased

Answer 4

bonds broken, secondary and tertiary structure changed, protein denatured

Question 5

how does the structure of membranes vary in organisms at high and low temperatures

Answer 5

high temp - increased cholesterol, less unsaturated fatty acids in phospholipids
low temp - decreased cholesterol, more unsaturated fatty acids in phospholipids (more kinks)

Question 6

describe and explain the effect of organic solvents on membrane permeability

Answer 6

organic solvents are less polar than water and can dissolve lipids. ethanol dissolves the lipids in the cell membrane, which means the membrane loses its structure.
increasing the concentration of the solvent will increase permeability of membranes

Question 7

what is the effect of very strong alcohol solutions

Answer 7

destroy cells

Question 8

why is alcohol found in antiseptic wipes

Answer 8

will dissolve membranes of bacteria, killing them and reducing infection

Question 9

why does water not disrupt cell membranes

Answer 9

it is polar and cannot dissolve phospholipids